The proposed project is designed to explore the effect of cocaine abuse on audition. Effect of acute cocaine administration and chronic cocaine addiction on the peripheral end-organ, namely, the cochlea, will be studied by recording N response from the round window. The amplitude-intensity functions will be used to assess the effect of cocaine on the N1 response. Tuning curves obtained with the N1 response will be used to assess the effect of cocaine on the different frequency regions of the cochlea. Also, the effect of different dosage levels of cocaine on the N1 will be evaluated. The integrity of the efferent system and the sympathetic system in the peripheral end-organ under the influence of acute and chronic cocaine administration will be studied in an attempt to investigate the mechanisms involved.